Yu Li, Gao Guoying, Zhu Lin, Deng Lei, Yang Zhizong, Yao Kailun
School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China.
Phys Chem Chem Phys. 2015 Jun 14;17(22):14986-93. doi: 10.1039/c5cp01508a.
Critical thickness for ferroelectricity and the magnetoelectric effect of Co2FeAl/BaTiO3 multiferroic tunnel junctions (MFTJs) are investigated using first-principles calculations. The ferroelectric polarization of the barriers can be maintained upto a critical thickness of 1.7 nm for both the Co2/TiO2 and FeAl/TiO2 interfaces. The magnetoelectric effect is derived from the difference in the magnetic moments on interfacial atoms, which is sensitive to the reversal of electric polarization. The magnetoelectric coupling is found to be dependent on the interfacial electronic hybridizations. Compared with the Co2/TiO2 interface, more net magnetization change is achieved at the FeAl/TiO2 interface. In addition, the in-plane strain effect shows that in-plane compressive strain can lead to the enhancement of ferroelectric polarization stability and intensity of magnetoelectric coupling. These findings suggest that Co2FeAl/BaTiO3 MFTJs could be utilized in the area of electrically controlled magnetism, especially the MFTJ with loaded in-plane compressive strain with the FeAl/TiO2 interface.
利用第一性原理计算研究了铁电临界厚度以及Co2FeAl/BaTiO3多铁隧道结（MFTJs）的磁电效应。对于Co2/TiO2和FeAl/TiO2界面，势垒的铁电极化在高达1.7 nm的临界厚度时都能保持。磁电效应源于界面原子磁矩的差异，其对电极化的反转很敏感。发现磁电耦合取决于界面电子杂化。与Co2/TiO2界面相比，FeAl/TiO2界面实现了更大的净磁化强度变化。此外，面内应变效应表明，面内压缩应变可导致铁电极化稳定性增强以及磁电耦合强度提高。这些发现表明，Co2FeAl/BaTiO3 MFTJs可用于电控磁性领域，特别是具有FeAl/TiO2界面且加载面内压缩应变的MFTJ。
